Time-Domain Measurement of Optical True-Time Delay in Two-Dimensional Photonic Crystal Waveguides

We report on the realization of optical true-time delay （TTD） by a two-dimensional photonic crystal waveguide （PCWG）. Design and fabrication of the PCWG are investigated. The spectral dependence of the group delay is measured by detecting the phase shifts of a 10 GHz modulating signal, and a maximum delay of 25±2.5 ps is obtained.     

Theoretical and Experimental Investigation of Flexural Wave Propagating in a Periodic Pipe with Fluid-Filled Loading

Based on the Bragg scattering mechanism of phononic crystals （PCs）, a periodic composite material pipe with fluid loading is designed and studied. The band structure of the flexural wave in the periodic pipe is calculated with the transfer matrix （TM） method. A periodic piping experimental system is designed, and the vibration experiment is performed to validate the attenuation ability of the periodic pipe structure. Finally, a finite-element pipe model is constructed using the MSC-Actran software, and the calculated results match well with the vibration experiment. The errors between the theoretical calculation results and the vibration experimental results are analyzed.     

Inhomogenous Dislocation Nucleation Based on Atom Potential in Hexagonal Noncentrosymmetric Crystal Sheet

By introducing internal degree, the deformation of hexagonal noncentrosymmetric crystal sheet can be described by the revised Cauchy-Born rule based on atomic potential. The instability criterion is deduced to investigate the inhomogeneous dislocation nucleation behavior of the crystal sheet under simple loading. The anisotropic characters of dislocation nucleation under uniaxial tension are studied by using the continuum method associated with the instability criterion. The results show a strong relationship between yield stress and crystal sheet chirality. The results also indicate that the instability criterion has sufficient ability to capture the dislocation nucleation site and expansion. To observe the internal dislocation phenomenon, the prediction of the dislocation nucleation site and expansion domain is illustrated by MD simulations. The developed method is another way to explain the dislocation nucleation phenomenon.     

Slow Light Effect and Multimode Lasing in a Photonic Crystal Waveguide Microlaser

The slow light effect in a photonic crystal waveguide is investigated theoretically and experimentally. Theoretical calculation indicates that there is a slow light region for the even mode, from which the resonance and lasing in a microcavity would benefit. A photonic crystal waveguide microlaser is fabricated, which is related to the group velocity of c/120.6.     

White Emitting ZnS Nanocrystals： Synthesis and Spectrum Characterization

Spherical organic-bonded ZnS nanocrystals with 4.0 4-0.2 nm in diameter are synthesized by a liquid-solid-solution method. The photoluminescence spectrum of sample （[S^2-]/[Zn^2＋] = 1.0） shows a strong white emission with a peak at 490nm and - 170 nm full widths at half maximum. By Gauss fitting, the white emission is attributed to the overlap of a blue emission and a green-yellow emission, originating from electronic transitions from internal S^2- vacancies level to valence band and to the internal Zn^2＋ vacancy level, respectively. After sealingZnS nanocrystals onto InGaN chips, the device shows CIE coordinates of （0.29,0.30）, which indicates their potential applications for white light emitting diodes.     

光子晶体光纤中超连续谱的研究进展与应用

利用光子晶体光纤(photonic crystal fiber,PCF)产生超连续光谱是目前光通信光电子器件领域的一个研究热点,文章系统地介绍了石英光子晶体光纤和非石英软玻璃光子晶体光纤中产生超连续谱的理论和实验研究成果.对于石英光子晶体光纤主要介绍了实芯光子晶体光纤、空芯填充光子晶体光纤和锥形光子晶体光纤产生超连续谱的研究成果,分类介绍了其超连续谱产生的特点.对于非石英光子晶体光纤主要介绍了某些铅硅酸盐玻璃和亚碲酸盐玻璃光子晶体光纤超连续谱产生的特点.最后介绍了超连续谱的应用和发展前景.     

近化学计量比双掺铁锰铌酸锂晶体紫外光致吸收特性的研究

研究了不同锂含量的双掺铁锰铌酸锂晶体的紫外光致吸收特性,结果表明,同成分晶体的紫外光致吸收系数较低,随着锂含量的增加,晶体的紫外光致吸收系数逐渐增大,当晶体中的锂含量达到49.57mol%附近时,紫外光致吸收系数达到最大值4.20 cm-1,进一步增加晶体中的锂含量,饱和光致吸收系数开始下降。在此基础上,提出了近化学计量比双掺铁锰铌酸锂晶体的双色非挥发全息存储的三中心模型,即随着晶体锂含量的增加,双掺铁锰晶体的光折变中心除了Fe2+/Fe3+,Mn2+/Mn3+外,还将增加双极化子/小极化子中心。     

KH_2PO_4晶体的太赫兹-紫外光谱

实验测量了室温下磷酸二氢钾KH2PO4(KDP)晶体0.2～1.6THz的时域光谱,以及50～4000cm-1范围内的远红外光谱,200～2000nm的紫外-可见-红外光谱。KDP晶体的禁带宽度是5.91eV。在测量范围内有一个很宽的声子吸收带。从0.2～205.5THz吸收系数在35～80cm-1,声子吸收的低频端小于0.2THz。最高的纵光学模声子的频率νLO大约是205.5THz,由此求出这支声子的H—O键的力常数为13.13N·cm-1。     

光子晶体光纤的传输模式特性

基于平面波展开法,数值模拟高光子晶体光纤传输的几种模式,介绍光子晶体光纤的应用及发展.结论为光子晶体光纤通信的器件设计提供参考.     

面心立方结构三维光子晶体的带隙特性

选择ZnSe、CdTe、AIP和GaAs 4种材料设计构成面心立方三维光子晶体结构,基于平面波展开法通过计算,得到带隙存在于0Hz、0.8140-0.8406Hz、0.7924-0.8218Hz和0.7457-0.7837Hz范围,带隙宽度随着4种材料介电常数的增加而增加.研究结论为三维光子晶体的制备提供参考.